peak-only — relating to or occurring only during periods of highest demand or activity

a transit worker in uniform opens an additional ticket booth window as crowds of commuters surge forward. Long lines of people in business attire wait impatiently while checking their watches. The worker points to a schedule showing the extra booth only operates during morning and evening rush periods. During quiet afternoon hours shown in the background, the same booth window remains closed with barriers in front. Frustrated off-peak travelers stand nearby looking at the closed service window. Other commuters rush past toward the active main booth that stays open all day. services that operate only during periods of highest demand or activity